紅紙格子 Behind the Red Paper Lattice
不知他的心性如何？假若被他摩弄動了啊，留他在這裡也罷。」即展翅，飛到裡邊看處，那東廊下上明下暗的紅紙格子裡面，坐著唐僧哩。不知他的心性如何？假若被他摩弄动了啊，留他在这里也罢。」即展翅，飞到里边看处，那东廊下上明下暗的红纸格子里面，坐着唐僧哩。
逐句解 Line by line
"I wonder what state his mind is in?"
The question is startling and entirely serious. 心性 is the disposition of the heart-mind, the Buddhist term for a person's fundamental temper — Pilgrim is asking whether his master has been tempted.
"If he has let her work on him and move him, then he may as well be left here."
The two characters at the end are 也罷, read yě bà, the resigned so-be-it — not the light suggestion particle. 摩弄 is to handle and work at something until it gives, and Pilgrim's willingness to abandon his master on the strength of it is the coldest line he has spoken all chapter.
He spread his wings at once and flew inside to look, and there in the east corridor, behind a red paper lattice, light above and dark below, sat the Tang Monk.
The set of the scene is exact. A 格子 is a latticed window or screen; papered red and lit from above, it lets a shape be seen and not a face. Here 著 is zhe, the reading for a state held in place — he is not sitting down, he has been sitting.
Pilgrim's condition is worth stopping on, because it tells you what this novel thinks is at stake. He does not ask whether Tripitaka is hurt. He asks whether Tripitaka has wavered, and says that if he has, the rescue is off.
This is not cruelty so much as the logic of the whole journey. The pilgrimage is a training in not being moved, and a master who could be moved by a fiend in a flowered jacket would have failed the test the journey exists to set. The chapter is about to give us Tripitaka's answer, and it is furious.
The staging deserves its credit too. Red paper, light from above, dark below, a seated shape behind a lattice. The novel has spent a hundred characters on architecture and it cashes them in here for a single image of a man held in a bright box.